Replace more for loops in GN

tools/gn/path_output.cc

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "tools/gn/path_output.h"
 
 #include "build/build_config.h"
 #include "tools/gn/filesystem_utils.h"
 #include "tools/gn/output_file.h"
 #include "tools/gn/string_utils.h"
@@ skipping 59 matching lines @@
   }
 }
 
 void PathOutput::WriteFile(std::ostream& out, const OutputFile& file) const {
   // Here we assume that the path is already preprocessed.
   EscapeStringToStream(out, file.value(), options_);
 }
 
 void PathOutput::WriteFiles(std::ostream& out,
                             const std::vector<OutputFile>& files) const {
-  for (size_t i = 0; i < files.size(); i++) {
+  for (const auto& file : files) {
     out << " ";
-    WriteFile(out, files[i]);
+    WriteFile(out, file);
   }
 }
 
 void PathOutput::WriteDir(std::ostream& out,
                           const OutputFile& file,
                           DirSlashEnding slash_ending) const {
   DCHECK(file.value().empty() ||
          file.value()[file.value().size() - 1] == '/');
 
   switch (slash_ending) {
@@ skipping 62 matching lines @@
     // it's system-absolute.
 #if defined(OS_WIN)
     // On Windows, trim the leading slash, since the input for absolute
     // paths will look like "/C:/foo/bar.txt".
     EscapeStringToStream(out, str.substr(1), options_);
 #else
     EscapeStringToStream(out, str, options_);
 #endif
   }
 }